netlify-cli/functions-templates/typescript/set-res-header/{{name}}.ts

Netlify command line tool

import type { Context } from 'https://edge.netlify.com'

export default async (request: Request, context: Context) => {
  const response = await context.next()
  response.headers.set('X-Your-Custom-Header', 'A custom value')
  return response
}